Electrochemical etching method and electrochemical etching device
By metallizing the back of the material with poor conductivity before electrochemical etching, and powering on to control the potential and consistency during the etching process, the problem of etching is solved, and the uniformity and stability of the etching rate are achieved.
Patent Information
- Application Number
- CN202311118460.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-08-31
- Publication Date
- 2025-02-28
AI Technical Summary
When electrochemical etching on materials with poor conductivity, the etching object will have a serious edge effect, resulting in uneven etching and the etching rate cannot be accurately controlled.
Before electrochemical etching, the back of the etching object is metalized to form a metal layer, and during the etching process, power is supplied to the metal layer to ensure that the potentials at all sides of the etching object are consistent.
The resistance of the etching object is reduced through metallization, the edge effect is avoided, the consistency of the electric potentials of the etching object is achieved, the uniformity of the etching rate is ensured, and the difficulty of electrochemical etching of materials with poor conductivity is reduced.
Smart Images
Figure CN119542132A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor processing technology, and more specifically, to an electrochemical etching method and an electrochemical etching device. Background Art
[0002] Electrochemical etching has great application potential in semiconductor processing because it can accurately control the etching rate. Electrochemical etching requires that the etched object has good conductivity. When the conductivity of the etched object is poor, the etched object will produce serious edge effects during electrochemical etching. Specifically, the voltage in the middle area of the etched object is too different from the voltage in the edge area, and the potential at various locations on the surface of the etched object cannot be accurately controlled. Therefore, electrochemical etching has poor etching uniformity for etched objects with poor conductivity and cannot be widely used in semiconductor processing. Summary of the invention
[0003] In order to solve the above problems existing in the prior art, the present invention provides an electrochemical etching method and an electrochemical etching device.
[0004] The present invention solves the above technical problems through the following technical solutions:
[0005] An electrochemical etching method, comprising:
[0006] Performing metallization treatment on the back side of the etching object that does not need to be etched, so as to form a metal layer on the back side of the etching object;
[0007] The front side of the etching object to be etched is subjected to electrochemical etching treatment.
[0008] Preferably, before metallizing the back side of the etching object which does not need to be etched, a barrier layer is deposited on the back side of the etching object.
[0009] Preferably, before depositing a barrier layer on the back side of the etching object, the back side of the etching object is cleaned.
[0010] Preferably, after electrochemical etching is performed on the front side of the etching object to be etched, the method further comprises:
[0011] removing the metal layer on the back side of the etching object;
[0012] The barrier layer on the back side of the etching object is removed.
[0013] Preferably, after the electrochemical etching is performed on the front side of the etching object to be etched, the method further includes removing the metal layer on the back side of the etching object.
[0014] Preferably, the thickness of the metal layer is greater than or equal to 10 nm.
[0015] Preferably, the material of the barrier layer is any one of tantalum oxide, tantalum nitride, tantalum, titanium, titanium nitride and cobalt.
[0016] Preferably, the thickness of the barrier layer is less than or equal to 1 nm.
[0017] Preferably, in the step of performing electrochemical etching on the front side of the etching object to be etched, power is supplied to the metal layer in a surface contact manner.
[0018] Preferably, in the step of performing electrochemical etching on the front surface of the etching object to be etched, the etching solution used in the electrochemical etching is any one of KOH, HF and TMAH.
[0019] Preferably, in the step of electrochemically etching the front side of the etching object to be etched, the etching object is placed on a chuck of an electrochemical etching device by edge clamping.
[0020] An electrochemical etching device, comprising:
[0021] A coating module, used for performing metallization treatment on the back side of the etching object to form a metal layer on the back side of the etching object;
[0022] An electrochemical etching module, used for performing electrochemical etching on the front side of the etching object;
[0023] Control module, including:
[0024] A transmission mechanism, used for transmitting the etching object to the coating module, and transferring the etching object from the coating module to the electrochemical etching module;
[0025] A controller, used for sending working instructions to the transmission mechanism, the plating module and the electrochemical etching module;
[0026] The controller controls the transmission mechanism to first transfer the etching object to the coating module. When the etching object reaches the coating module, the controller sends a working instruction to the coating module, and the coating module performs metallization on the back of the etching object.
[0027] After the coating module finishes working, the controller controls the transmission mechanism to transfer the etching object from the coating module to the electrochemical etching module;
[0028] When the etching object reaches the electrochemical etching module, the controller sends a working instruction to the electrochemical etching module to control the electrochemical etching module to perform electrochemical etching on the front side of the etching object.
[0029] The positive and progressive effects of the present invention are as follows: in the present invention, before the electrochemical etching treatment, the back side of the etching object is first metallized, which can greatly reduce the resistance of the etching object, thereby effectively avoiding the edge effect of the etching object; during the electrochemical treatment, by energizing the metal layer on the back side of the etching object, the electric potential at various locations on the surface of the etching object can be accurately controlled, so that the electric potential at various locations on the etching object remains consistent, avoiding uneven current density distribution during the etching process, and then accurately controlling the etching rate of the etching object, greatly reducing the difficulty of electrochemical etching of etching objects with poor conductivity. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The features and properties of the present invention are further described by the following embodiments and the accompanying drawings.
[0031] Figure 1 Schematic diagram of the process of the electrochemical etching method of Example 1 of the present invention;
[0032] Figure 2 Schematic diagram of the process of the electrochemical etching method of Example 2 of the present invention. DETAILED DESCRIPTION
[0033] In order to explain the technical content, structural features, objectives and effects of the present invention in detail, the following will be described in detail in conjunction with embodiments and drawings, but the present invention is not limited to the scope of the embodiments.
[0034] Example 1
[0035] The electrochemical etching process can accurately control the etching rate by selecting a suitable electrolyte and controlling the potential and current of the working electrode. Therefore, the electrochemical etching process has great application potential in semiconductor processing. The object of electrochemical etching is usually a material with good conductivity. The potential consistency at different positions of the material with good conductivity is good, and the etching uniformity is good. For materials with poor conductivity, the area with large resistance is easy to form a higher local potential during the etching process, resulting in uneven etching. In addition, poor conductivity will also cause a decrease in etching rate and prolong etching time. For example, silicon has poor conductivity. Even if it is cut into small pieces of 2cm*2cm, the resistance is as high as 1MΩ. Materials with poor conductivity usually increase the etching rate by increasing the voltage during electrochemical etching, but the uniformity of etching cannot be solved. At present, there is no better method for electrochemical etching of materials with poor conductivity.
[0036] The embodiment of the present invention provides an electrochemical etching method, which can be applied to materials with poor conductivity. The etching object in the embodiment of the present invention is a silicon wafer, but of course, the etching object is not limited thereto and can also be other materials with poor conductivity.
[0037] Electrochemical etching methods such as Figure 1 As shown, the following steps are included:
[0038] S100, performing metallization treatment on the back side of the silicon wafer that does not need to be etched, and forming a metal layer on the back side of the silicon wafer.
[0039] S200, performing electrochemical etching on the front side of the silicon wafer that needs to be etched.
[0040] Before the electrochemical etching process, the back of the silicon wafer is first metallized, which can greatly reduce the resistance of the silicon wafer, thereby effectively avoiding the edge effect of the silicon wafer. During the electrochemical treatment, by energizing the metal layer on the back of the silicon wafer, the electric potential at various locations on the surface of the silicon wafer can be accurately controlled, so that the electric potential at various locations on the silicon wafer remains consistent, avoiding uneven current density distribution during the etching process, and thus making the electrochemical etching rate on the front of the silicon wafer consistent. Therefore, this embodiment greatly reduces the difficulty of etching silicon wafers by electrochemical methods, optimizes the performance and effect of the electrochemical silicon etching process, and enables the process of etching silicon wafers by electrochemical methods to be mass-produced.
[0041] In this embodiment, metals with good electrical conductivity, such as copper, silver, aluminum, etc., are selected.
[0042] The thickness of the metal layer is greater than or equal to 10nm. A thicker metal layer can provide lower resistance, enhance the conductivity of the etched object, and maintain the same potential at all locations of the etched object after power is applied. The metal layer is not easily damaged during power application, which is beneficial to improving the stability of the electrochemical etching process. In addition, a thicker metal layer can provide better structural support and stability to a certain extent, which can increase the mechanical strength of the back of the etched object and reduce the risk of deformation or cracking.
[0043] In step S200, the metal layer is supplied with power by means of surface contact, which is less likely to damage the metal layer than point contact and provides more stable power supply.
[0044] In step S200, the etching solution used in the electrochemical etching is any one of KOH, HF and TMAH.
[0045] In step S200, the etching object is placed on the chuck of the electrochemical etching device by edge clamping, which can avoid damage to the metal layer on the back of the etching object, thereby affecting the difference in resistance on the back of the etching object and ultimately affecting the uniformity of electrochemical etching.
[0046] In this embodiment, the silicon wafer is metallized by deposition, and a metal layer is grown on the surface of the silicon wafer. Since the metal may invade the silicon wafer during the metallization process, affecting the subsequent production process, step S90 is included before step S100, in which a barrier layer is deposited on the back of the silicon wafer. The diffusion of the metal can be effectively controlled by depositing the barrier layer to prevent the metal from entering the interior of the silicon wafer. In addition, good metal adhesion can be provided by depositing the barrier layer. The barrier layer can increase the adhesion between the metal and the back of the silicon wafer, ensuring good contact between the metallization layer and the back of the silicon wafer.
[0047] The material of the barrier layer may be any one of tantalum oxide, tantalum nitride, tantalum, titanium, titanium nitride and cobalt.
[0048] In addition, the thickness of the barrier layer needs to be less than or equal to 1 nm. The thin thickness of the barrier layer can prevent the metal layer from diffusing into the interior of the etched object, and at the same time ensure the consistency of the potential at various locations of the etched object after power is turned on.
[0049] In addition, before step S90, step S80 is also included, in which the back side of the silicon wafer is cleaned. This step is beneficial to remove impurities on the back side of the silicon wafer and enhance the bonding between the barrier layer and the silicon wafer.
[0050] Finally, after S200 also includes:
[0051] S300, removing the metal layer on the back side of the silicon wafer.
[0052] S400, removing the barrier layer on the back side of the silicon wafer.
[0053] Of course, if the metal layer needs to be retained after etching is completed, S300 and S400 may not be performed.
[0054] Example 2
[0055] In this embodiment of the invention, if the metal is not easy to penetrate into the interior of the etching object when the back side of the etching object is metallized, then S90 is not required. Figure 2 As shown, the electrochemical etching method at this time includes:
[0056] S100, performing metallization treatment on the back side of the silicon wafer that does not need to be etched, so as to form a metal layer on the back side of the silicon wafer;
[0057] S200, performing electrochemical etching on the front side of the silicon wafer that needs to be etched;
[0058] S300, removing the metal layer on the back side of the silicon wafer.
[0059] In this embodiment, aluminum may be selected as the metal layer for deposition, wherein the aluminum is doped with 1%-2% silicon.
[0060] In other embodiments, the method of metallizing the back side of the silicon wafer is not limited thereto, and a metal sheet with a relatively high surface flatness may be prepared and directly bonded to the back side of the silicon wafer.
[0061] Of course, if the metal layer needs to be retained after the etching is completed, S300 may not be performed.
[0062] Of course, in this embodiment, the back side of the silicon wafer may also be cleaned before S100 to increase the bonding ability between the metal layer and the silicon wafer.
[0063] Example 3
[0064] An embodiment of the present invention provides an electrochemical etching device, which includes a coating module, an electrochemical etching module and a control module. The coating module is used to perform metallization treatment on the back side of the etching object to form a metal layer on the back side of the etching object, and the electrochemical etching module is used to perform electrochemical etching treatment on the front side of the etching object.
[0065] The control module includes: a transmission mechanism, which is used to transmit the etching object to the coating module, and to transfer the etching object from the coating module to the electrochemical etching module; a controller, which is used to send work instructions to the transmission mechanism, the coating module and the electrochemical etching module; the controller controls the transmission mechanism to first transmit the etching object to the coating module, and when the etching object reaches the coating module, the controller sends a work instruction to the coating module, and the coating module performs metallization treatment on the back of the etching object; after the coating module finishes working, the controller controls the transmission mechanism to transfer the etching object from the coating module to the electrochemical etching module; when the etching object reaches the electrochemical etching module, the controller sends a work instruction to the electrochemical module, and controls the electrochemical etching module to perform electrochemical etching treatment on the front of the etching object.
[0066] The plating module can use an existing electroplating device to perform metallization treatment on the back of the etching object by electroplating. The electrochemical etching module can use an existing electrochemical etching machine. The transmission mechanism can use an existing transmission system, such as a manipulator.
[0067] Before the electrochemical etching module etches the front side of the etching object, the back side of the etching object is first metallized by the plating module to reduce the resistance of the back side of the etching object, so that the electric potential at various locations on the surface of the etching object can be accurately controlled to keep the electric potential at various locations of the etching object consistent, thereby avoiding uneven current density distribution during the etching process, and thus keeping the electrochemical etching rate at the front side of the etching object consistent.
[0068] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that these are only examples, and various changes or modifications may be made to these embodiments without departing from the principles and essence of the present invention. Therefore, the protection scope of the present invention is limited by the appended claims.
Claims
1. An electrochemical etching method, characterized in that: include: Performing metallization treatment on the back side of the etching object that does not need to be etched, so as to form a metal layer on the back side of the etching object; The front side of the etching object to be etched is subjected to electrochemical etching treatment.
2. The electrochemical etching method according to claim 1, characterized in that: Before metallizing the back side of the etching object which does not need to be etched, a barrier layer is deposited on the back side of the etching object.
3. The electrochemical etching method according to claim 2, characterized in that: Before depositing a barrier layer on the back side of the etching object, the back side of the etching object is cleaned.
4. The electrochemical etching method according to claim 2, characterized in that: After the front side of the etching object to be etched is subjected to electrochemical etching, the method further comprises: removing the metal layer on the back side of the etching object; The barrier layer on the back side of the etching object is removed.
5. The electrochemical etching method according to claim 1, characterized in that: After the front side of the etching object to be etched is subjected to electrochemical etching, the method further includes removing the metal layer on the back side of the etching object.
6. The electrochemical etching method according to claim 1, characterized in that: The thickness of the metal layer is greater than or equal to 10 nm.
7. The electrochemical etching method according to claim 2, characterized in that: The material of the barrier layer is any one of tantalum oxide, tantalum nitride, tantalum, titanium, titanium nitride and cobalt.
8. The electrochemical etching method according to claim 2, characterized in that: The thickness of the barrier layer is less than or equal to 1 nm.
9. The electrochemical etching method according to claim 1, characterized in that: In the step of performing electrochemical etching on the front side of the etching object to be etched, power is supplied to the metal layer in a surface contact manner.
10. The electrochemical etching method according to claim 1, characterized in that: In the step of electrochemically etching the front side of the etching object to be etched, the etching solution used in the electrochemical etching is any one of KOH, HF and TMAH.
11. The electrochemical etching method according to claim 1, characterized in that: In the step of electrochemically etching the front side of the etching object to be etched, the etching object is placed on a chuck of an electrochemical etching device by edge clamping.
12. An electrochemical etching device, characterized in that: The device comprises: A coating module, used for performing metallization treatment on the back side of the etching object to form a metal layer on the back side of the etching object; An electrochemical etching module, used for performing electrochemical etching on the front side of the etching object; Control module, including: A transmission mechanism, used for transmitting the etching object to the coating module, and transferring the etching object from the coating module to the electrochemical etching module; A controller, used for sending working instructions to the transmission mechanism, the plating module and the electrochemical etching module; The controller controls the transmission mechanism to first transfer the etching object to the coating module. When the etching object reaches the coating module, the controller sends a working instruction to the coating module, and the coating module performs metallization on the back of the etching object. After the coating module finishes working, the controller controls the transmission mechanism to transfer the etching object from the coating module to the electrochemical etching module; When the etching object reaches the electrochemical etching module, the controller sends a working instruction to the electrochemical etching module to control the electrochemical etching module to perform electrochemical etching on the front side of the etching object.